Aussie upstart Courtney Barnett takes root with “Avant Gardener.”

It sounds like a bad dream or a great bit of creative writing, but the physical breakdown described in Courtney Barnett’s “Avant Gardener” came out of real life — and pretty much happened the way she describes it in the song that has made her a darling of the indie-rock world.

Asked about the incident two weeks ago via ­Skype from Barcelona — a sign of the globe-trotting year she’s enjoying — the 26-year-old former bartender was quick to defend her horticulture skills.

“I sort of grew up in the bush, so I’d definitely spent a lot of time working outside,” said Barnett, talking in the same free-flowing manner in which she sings. “It was really hot and I might’ve had some kind of allergic reaction. I spent the night in the hospital but everything was OK in the end.”

Of course, the gardening is on hold now that Barnett’s career is in full bloom and she’s touring full-time, including a U.S. jaunt that lands Tuesday at the Varsity Theater.

This spring, she quit her bartending job for good, made a splash at Coachella and toured as Billy Bragg’s opener (“a super nice guy, and a total inspiration,” she said). With “Avant Gardener” already in heavy rotation at 89.3 the Current, her two debut mini-albums were released stateside as one album in May, “The Double EP: A Sea of Split Peas,” via Mom + Pop Records (see: Metric, Sleigh Bells).

Despite solid reviews pointing to a cohesive debut, Barnett said she still sees her EPs as two distinct collections.

“I wrote and recorded the first one in my bedroom and then just showed it to friends to help me get it out,” she said. “The second one came after we did a little bit of touring, and then we got a nice little bit of grant money from the government to spend on recording.”

That’s right: The Australian government helped fund the debut recording of one of its newest music stars. “Americans are always surprised when they hear that,” she said.

Barnett finished what will be her proper full-length debut with her band just last month before returning to tour mode. She said simply of the new record, “It’s another year full of ideas, with hopefully a step up musically.”

“A Sea of Split Peas” is still fresh on fans’ playlist, though. It ranges stylistically from slow-grooving Velvet Underground-style rockers such as “Don’t Apply Compression Gently” to the lazy-day ballad “Anonymous Club” to the punkier blaster “History Eraser.” Barnett’s unique singing/lyrical style is up front and left-of-center through it all.

One of her best-loved traits has been her seemingly stream-of-conscious songwriting, but she said her songs usually only start out as off-the-cuff. “I take the time to refine them later,” she conceded.

As with “Avant Gardener,” though, the songs on her EPs mostly came straight out of her daily life, including the romantic adventures in “History Eraser” and even the sweet musical discovery in the closing track “Ode to Odetta.” She got turned on to the late folk singer one day on the job while watching a Bob Dylan documentary.

Along the same lines, the reference to Uma Thurman’s adrenaline-shot scene from “Pulp Fiction” popped up in the lyrics to “Avant Gardener” as a byproduct of her job, she said: “It’s just one of those movies you always wind up watching after you get off late from the bar and are pretty drunk, but you don’t want to go to bed.”